/Engine/Source/Runtime/Engine/Classes/Engine/AssetManager.h
Gets list of all loaded objects for a primary asset type, returns true if any were found. Will return blueprint class for blueprint assets. This works even if the asset wasn't loaded explicitly
virtual bool GetPrimaryAssetObjectList ( [FPrimaryAssetType](API\Runtime\CoreUObject\UObject\FPrimaryAssetType) PrimaryAssetType, [TArray](API\Runtime\Core\Containers\TArray)< [UObject](API\Runtime\CoreUObject\UObject\UObject) * > & ObjectList ) const